1. Field of Invention
The present invention relates to a signal line structure. More particularly, the present invention relates to a signal line structure of a flat display.
2. Description of Related Art
Regarding the developing of display technology, novel displays have been used in portable computer, mobile phone, digital camera and other electronic products. Among those displays, flat display is the most potential displays.
FIG. 1 is a cross-sectional view of a typical flat display device. Flat display device 100 comprises a first substrate 110 with a thin film transistor array, a second substrate 120, a material layer 130 and a transparent electrode layer 140. The transparent electrode layer 140 is made of indium tin oxide (ITO), indium zinc oxide (IZO) or other transparent conducting materials. The material layer 130 is formed between the transparent electrode layer 140 and the pixel electrode 112 of the thin film transistor array in the first substrate 110. The optical property of each pixel in the display device 100 can be modified by changing the electric field between the pixel electrode 112 and the transparent electrode layer 140.
FIG. 2 is a top view of the flat display device 100 in FIG. 1. The flat display device 100 comprises a display area 102 and a peripheral circuit area 104 surrounding the display area 102. Data lines 154 and scan lines 152 disposed on the display area 102 to divide the display area 102 into a plurality of pixel areas 110a. Thin film transistors 114 and pixel electrodes 112 are formed in the pixel area 110a. The thin film transistors 114 are connected to corresponding scan lines 152 and data lines 154. The pixel electrodes 112 are connected to the thin film transistors 114. A plurality of gate drivers 142 and source drivers 144 are formed on the peripheral circuit device 104. The gate drivers 142 connected to scan lines 152 transmit driving signal from scan lines 152 to the gates of the thin film transistors 114 and turn on the thin film transistor 114 when displaying images. Source drivers 144 connected to data lines 154 are able to transmit image data to the pixel electrodes 112 when the thin film transistors 114 are turned on.
FIG. 3 is an enlarged diagram of the area in the gate driver. For saving the area of the peripheral circuit device 104, the separated distance A between two adjacent scan lines, such as scan line 152a and scan line 152b, located in the area 156 is required to reduce. In such structure, when a high level drive voltage signal is transferred to the scan line 152a, a low level drive voltage signal is transferred to the scan line 152b. A voltage difference is generated between the scan line 152a and the scan line 152. When the distance A is further reduced, the voltage difference will generate a huge electric field that causes the scan line 152a and the scan line 152 being etched broken to affect the transmission of the drive signal thereon.
Therefore, a signal line structure that can prevent the etching situation is required.